A new density-functional approach to calculate the excitation spectrum of many-electron systems is proposed. It is shown that the full linear density response of the interacting system, which has poles at the exact excitation energies, can rigorously be expressed in terms of the response function of the noninteracting (Kohn-Sham) system and a frequency-dependent exchange-correlation kernel. Usi...

We report on the first fabrication of ~In,Ga!As/GaAs quantum dots with both vertical and lateral ordering forming a three-dimensional array. An investigation of the photoluminescence spectra from the ordered array of quantum dots, as a function of both temperature and optical excitation intensity, reveals both a lateral and vertical transfer of excitation. © 2003 American Institute of Physics. ...

An investigation is described of the hydroelastically coupled motion a cylindrical tank partially filled with liquid in response to travelling seismic wave excitation. The continuous phase variation vertical excitation along base causes flexible wall vibration modes positive circumferential numbers. stress analysis for this crucial case conducted paper. analytical explanation velocity dependenc...

By using functional integral methods we determine new types of differential equations satisfied by the joint response excitation probability density function associated with the stochastic solution to first-order nonlinear scalar PDEs. The theory is developed for arbitrary fully nonlinear and for quasilinear first-order stochastic PDEs subject to random boundary conditions, random initial condi...

In this paper, the nonlinear transient vibration of a cylindrical shallow panel under lateral white noise excitation is studied. The panel is in contact with a non aging viscoelastic medium. Since the external load is a time varying random wide band process, deterministic and conventional approaches cannot be used. Instead, the evolution of the probability density function of the response is in...

In this research, the modal parameters of a beam in free-free condition are extracted by performing different experiments in laboratory. For this purpose, two different techniques are employed. The first methodology is considered as a time domain method in Operational Modal Analysis. While the other one is frequency domain impact hammer test which is categorized as an Experimental Modal Analysi...

The paper describes the design of broadband chirp excitation pulses. We first develop a three stage model for understanding chirp excitation in NMR. We then show how a chirp π pulse can be used to refocus the phase of the chirp excitation pulse. The resulting magnetization still has some phase dispersion in it. We show how a combination of two chirp π pulses instead of one can be used to elimin...

The excitatory effect of different test stimuli was quantified in a large sample of primary auditory units of the starling. In order to construct an excitation pattern, the level of excitation in many single units in response to a specific test stimulus was plotted as a function of their characteristic frequency (CF). The effects of stimulus frequency and stimulus sound-pressure level on the sh...